Forward declaration of C# types in managed C++ headers

[Eckart Haug]

I'm working with C# objects from managed C++ using the gcroot template.
There'a a C++ header containing the definition of a C++ class:

#using <mscorlib.dll >
#include <vcclr.h>
#using <CSharpModule.d ll>

class CPlusPlusClass
{
....

gcroot<TLNameSp ace::SubNameSpa ce::SomeType*> _csharpInstance ;

....
}
and a C++ source file containing the class definition
#include "CPlusPlusClass .h"
using namespace TLNameSpace::Su bNameSpace;
void CPlusPlusClass: :createCSharp()
{
gcroot = new SomeType();
}

void CPlusPlusClass: :doSomething()
{
gcroot->someCSharpMeth od();
}

.....
In this example, I need the #using <CSharpModule.d ll> directive in the C++ header. One way to avoid this is
to split CPlusPlusClass into CPlusPlusInterf ace and CPlusPlus Implementation.
A more elegant technique in C++ would be a forward declaration for TLNameSpace::Su bNameSpace::Som eType in
the C++ header. However, I didn't find out how to do this.
The most promising try was

namespace TLNameSpace {
namespace SubNameSpace {
__gcc class SomeType;
}
}

At least the header compiled. On the #using <CSharpModule.d ll> line, I got an 'already defined' error.
Obviously C++ and C# namespaces are just a little bit the same ....

My question is:

- Is there a way to do the forward declaration described above ?
I'd appreciate any hint/solution for this

[Vladimir Nesterovsky]

You can add your C# assembly in a project's references thus you may not
import it explicitly.
--
Vladimir Nesterovsky
e-mail: vl******@nester ovsky-bros.com
home: http://www.nesterovsky-bros.com

I'm working with C# objects from managed C++ using the gcroot template.
There'a a C++ header containing the definition of a C++ class:

#using <mscorlib.dll >
#include <vcclr.h>
#using <CSharpModule.d ll>

class CPlusPlusClass
{
....

gcroot<TLNameSp ace::SubNameSpa ce::SomeType*> _csharpInstance ;

....
}
and a C++ source file containing the class definition
#include "CPlusPlusClass .h"
using namespace TLNameSpace::Su bNameSpace;
void CPlusPlusClass: :createCSharp()
{
gcroot = new SomeType();
}

void CPlusPlusClass: :doSomething()
{
gcroot->someCSharpMeth od();
}

.....
In this example, I need the #using <CSharpModule.d ll> directive in the C++
header. One way to avoid this is
to split CPlusPlusClass into CPlusPlusInterf ace and CPlusPlus
Implementation.
A more elegant technique in C++ would be a forward declaration for
TLNameSpace::Su bNameSpace::Som eType in
the C++ header. However, I didn't find out how to do this.
The most promising try was

namespace TLNameSpace {
namespace SubNameSpace {
__gcc class SomeType;
}
}

At least the header compiled. On the #using <CSharpModule.d ll> line, I got
an 'already defined' error.
Obviously C++ and C# namespaces are just a little bit the same ....

My question is:

- Is there a way to do the forward declaration described above ?
I'd appreciate any hint/solution for this

[Eckart Haug]

Thanx for the quick reply. Your suggestion would mean that I'd have to add a C# reference to any C++ module
that includes the C++ header. There's lots of them and I'd (for the moment) like to have the C++ <-> C#
interface encapsulated in one C++ module.

Vladimir Nesterovsky wrote:

You can add your C# assembly in a project's references thus you may not
import it explicitly.
--
Vladimir Nesterovsky
e-mail: vl******@nester ovsky-bros.com
home: http://www.nesterovsky-bros.com

I'm working with C# objects from managed C++ using the gcroot template.
There'a a C++ header containing the definition of a C++ class:

#using <mscorlib.dll >
#include <vcclr.h>
#using <CSharpModule.d ll>

class CPlusPlusClass
{
....

gcroot<TLNameSp ace::SubNameSpa ce::SomeType*> _csharpInstance ;

....
}
and a C++ source file containing the class definition
#include "CPlusPlusClass .h"
using namespace TLNameSpace::Su bNameSpace;
void CPlusPlusClass: :createCSharp()
{
gcroot = new SomeType();
}

void CPlusPlusClass: :doSomething()
{
gcroot->someCSharpMeth od();
}

.....
In this example, I need the #using <CSharpModule.d ll> directive in the C++
header. One way to avoid this is
to split CPlusPlusClass into CPlusPlusInterf ace and CPlusPlus
Implementatio n.
A more elegant technique in C++ would be a forward declaration for
TLNameSpace:: SubNameSpace::S omeType in
the C++ header. However, I didn't find out how to do this.
The most promising try was

namespace TLNameSpace {
namespace SubNameSpace {
__gcc class SomeType;
}
}

At least the header compiled. On the #using <CSharpModule.d ll> line, I got
an 'already defined' error.
Obviously C++ and C# namespaces are just a little bit the same ....

My question is:

- Is there a way to do the forward declaration described above ?
I'd appreciate any hint/solution for this

[Eckart Haug]

Thanx for the quick reply. Your suggestion would mean that I'd have to add a C# reference to any C++ module
that includes the C++ header. There's lots of them and I'd (for the moment) like to have the C++ <-> C#
interface encapsulated in one C++ module.

Vladimir Nesterovsky wrote:

You can add your C# assembly in a project's references thus you may not
import it explicitly.
--
Vladimir Nesterovsky
e-mail: vl******@nester ovsky-bros.com
home: http://www.nesterovsky-bros.com

I'm working with C# objects from managed C++ using the gcroot template.
There'a a C++ header containing the definition of a C++ class:

#using <mscorlib.dll >
#include <vcclr.h>
#using <CSharpModule.d ll>

class CPlusPlusClass
{
....

gcroot<TLNameSp ace::SubNameSpa ce::SomeType*> _csharpInstance ;

....
}
and a C++ source file containing the class definition
#include "CPlusPlusClass .h"
using namespace TLNameSpace::Su bNameSpace;
void CPlusPlusClass: :createCSharp()
{
gcroot = new SomeType();
}

void CPlusPlusClass: :doSomething()
{
gcroot->someCSharpMeth od();
}

.....
In this example, I need the #using <CSharpModule.d ll> directive in the C++
header. One way to avoid this is
to split CPlusPlusClass into CPlusPlusInterf ace and CPlusPlus
Implementatio n.
A more elegant technique in C++ would be a forward declaration for
TLNameSpace:: SubNameSpace::S omeType in
the C++ header. However, I didn't find out how to do this.
The most promising try was

namespace TLNameSpace {
namespace SubNameSpace {
__gcc class SomeType;
}
}

At least the header compiled. On the #using <CSharpModule.d ll> line, I got
an 'already defined' error.
Obviously C++ and C# namespaces are just a little bit the same ....

My question is:

- Is there a way to do the forward declaration described above ?
I'd appreciate any hint/solution for this